Cleaning of rails

ABSTRACT

A METHOD AND APPARATUS IS PROVIDED FOR TREATING RAILS BY PLASMA TORCH TO IMPROVE WHEEL/RAIL ADHENSION. THE POWER SUPPLIED TO THE TORCH IS REGULATED AUTOMATICALLY SO THAT IT IS APPROXIMATELY PROPORTIONAL TO THE SQUARE ROOT OF THE SPEED AT WHICH THE VEHICLE PASSES ALONG THE RAIL.

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[72] inventors David John Miller Dobbs; [56] References Cited Derek Linder, London, England UNITED STATES PATENTS [21] P i 1,101,503 6/1914 Joyce 104/279 [221 5" d J 1971 2,890,970 6/1959 Allen 104/279x [45] F "3? 3,479,471 11/1969 Smith et a1 219/121x [73] Assignee Britlsh Railways Board London, England FOREIGN PATENTS [32] Priority Apr. 17, 1968 54,144 10/1967 Poland 219/121? [33] Great Bmain Primary Examiner-J. V. Truhe [31] 18135] 68 Assistant Examiner-C. l... Albritton Attorney-Sommers & Young [54] CLEANING OF RAILS 5 Clams 2 Drawmg ABSTRACT: A method and apparatus is provided for treating [52) US. Cl 219/ 121?, rails by plasma torch to improve wheel/rail adhesion. The 104/279 power supplied to the torch is regulated automatically so that cl B231 9/00 it is approximately proportional to the quare root of the [50] Field of Search 104/279; speed-at which the vehicle passes along the rail.

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BLANKER CLEANING F RAILS SUMMARY OF THE INVENTION This invention concerns improvements relating to the cleaning of rails, particularly for the purpose of improving wheelrail adhesion of rail vehicles. It seeks to provide means whereby plasma arc techniques already proposed for this purpose can be applied with better effect than heretofore.

According to the invention, the supplied to a plasma torch carried upon a rail vehicle and arranged to act upon rail, or rail and wheel, is regulated automatically in dependence upon the speed at which the vehicle passes over the rail. Advantageously, the power supplied is regulated so that it is approximately proportional to the square root of the said speed, i.e. so that the law P=I S is approximately satisfied, where P and S are the said power and speed respectively and k is a constant.

With such regulation, the power will be adequate for cleaning the rail at any speed, but there will be less danger of damaging the rail or insulating track joints by the use at a lower speed of a level of power appropriate for use at a higher speed, or required for improving adhesion at such higher speed. Economy can be achieved, because the expenditure of power at any speed need be no greater than the minimum necessary to improve adhesion. Furthermore, the life of the torch components can be increased.

A system of regulation obeying a law of the form P=kS is more tolerant of inaccuracies in the supply of information to its control means than is one obeying a law of the form P=/ S. For example, if the speed information fed to the latter system were I00 percent inaccurate, the power supplied would be twice the value to which it should be regulated and serious risk of damage would exist. In the case of the former system, the power would only be 1.4 times the said value. There is therefore an inherent safeguard against damage to rails and track equipment.

At high speeds, with such regulation, the power consumption will be substantially smaller than in other cleaning systems, such as high-voltage spark cleaning, in which a linear relationship between power and speed is said to be maintained.

The invention will be more fully understood from the following description and accompanying drawings, in which:

FIG. I is an illustrative diagram of an apparatus constructed in accordance with, and adapted to practice the method of, the present invention; and

FIG. 2 is a graph showing certain operational aspects of the invention.

Referring to FIG. I, an AC tachometric generator I is coupled to a wheel axle ofa railway wheel, for example a locomotive, carrying the plasma torch 2, or torches, disposed in proximity to and directed upon the railhead. This generator provides a signal having a pulse frequency proportional to the speed of the vehicle or train. For example, such a generator may be mounted in an axle box and its rotor may be driven through a peg engaging a slot in a plate fastened to and rotating with the axle. The signal is supplied by way ofa pulse-shaping circuit 3 and an integrating circuit 4 to a diode function generator 5, or an operational amplifier with an appropriate transfer function, giving an output voltage which is proportional to the square root of the input, i.e. to the square root of the speed. The output is passed to a controlling winding of a linear transductor 6 or saturable reactor which controls the plasma torch current. If necessary, a linear amplifier may be incorporated in or added to the function generator for the purpose of amplifying the output to a level suitable for the transductor 6.

A speed meter 7 and/or recorder may be provided if required.

The current for the plasma torch 2 is supplied from a source 8 ofthree-phasc AC power through the controlled windings of the transductor 6 and a three-phase rectifying bridge 9. Additional, similarly controlled, plasma torch circuits may be supplied from the same source 8, as indicated at 10.

Assuming that the gas flow to the torch 2 is held constant,

the torch power will be proportional to the torch current, since the torch voltage is substantially constant. Consequently, the torch power will be substantially proportional to the square root of vehicle speed, i.e. P=kS' approximately, where P is the power, S the speed and k a function of the plasma gas used and ofthe rail-wheel adhesion required. It is a measure of the thermal efficiency of the system. Approximate values ofk for various gases and a minimum adhesion value of +0.3 over a 1.0 cm. wide band on the railhead are as follows:

Pure argon plasmas 20 Argon +l0 percent hydrogen 7 Nitrogen l 0 percent hydrogen 3 A curve illustrating typical results obtained in rail-cleaning tests in the track under normal operating conditions, using argon plus 10 percent hydrogen and a torch/rail spacing of 2.5 cm. for a minimum adhesion value, over a LG cm. wide band on the railhead, of +0.3 is shown in FIG. 2. In this FIGURE, the torch power P in kilowatts is plotted against the speed S of the torch in relation to the rail in miles per hour. The curve obtained approximately obeys the law P=kS" In place of the AC generator 1, use may be made of a DC tachometric generator producing an output voltage proportional to speed. This output is again processed in a function generator, whose output is then proportional to the square root of the said voltage.

We claim:

1. A method of treating a rail, to improve adhesion between said rail and the wheels ofa vehicle located on said rail, comprising the steps of positioning a plasma torch upon said vehicle so that said torch acts to heat said rail as said vehicle moves along the rail, supplying power to said torch, and automatically varying the power supplied to said torch with variations in the speed of said vehicle along said rail to increase said power with increases in vehicle speed and to decrease said power with decreases in vehicle speed, said power variation being such that the power supplied to said torch is substantially proportional to the square root of the speed of said vehicle along said rail.

2. An apparatus for treating a rail to improve the adhesion between said rail and the wheels of a vehicle located on said rail, comprising a vehicle adapted to be moved along a rail, a plasma torch carried by said vehicle and arranged to act upon said rail to heat said rail, power supply means electrically coupled to said torch, speed-responsive means carried by said vehicle and operative upon movement of said vehicle along said rail to provide an electrical signal dependent upon the speed of movement of said vehicle along said rail, and regulating means electrically coupled to said speed-responsive means and to said power supply means, said regulating means being responsive to said signal for controlling the power supplied to said torch from said power supply means substantially in proportion to the square root of said vehicle speed along said rail.

3. Apparatus according to claim 2, wherein a function-converting means is interposed between the said speed-responsive means and the said regulating means, the output of the said function-converting means being supplied to the said regulating means and being substantially proportional to the square root of the said speed.

4. Apparatus according to claim 2, wherein a function-converting means is interposed between the said speed-responsive means and the said regulating means, the said speed-responsive means being a tachometric generator whose outputis substantially proportional to the said speed, and the function-converting means being a function generator whose output is substantially proportional to the square root of the said speed.

5. Apparatus according to claim 2, wherein the regulating means is a transductor.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No- 34588 .441 Dated June 28 1971 Inventor) David John Miller Dobbs et al.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet the illustrative drawing should appear as shown below:

/0 6 ti} 2 F e AC 7 PMSMA 500K765 V rmwouc 0,? Y i row/,

5 FU/VCfiO/V game/4m? I 7 fll/Lff METIP/C //V7'E6FA7'0K f/YEPAWKJ Signed and sealed this 16th day of May 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FQRM "$59) uscoMM-Dc Guava-Pas a U 5 GOVERNMENT PHINYING OFFICE 1989 0-36533. 

